2 Solar String Inverters

Figure 2-1 shows the typical architecture of a solar string inverter.

Figure 2-1 Block Diagram of Solar String Inverter.

As Figure 2-1 illustrates, there are two major power blocks in the string inverter. The first is a DC/DC power stage that converts the variable string output to a stable high-voltage DC link suitable for DC/AC inverter stage. For a single phase power stage, it is typically 400 V and for three phase, around 800 V. This DC/DC stage also works as a Maximum Power Point Tracking (MPPT) converter. This DC link voltage is converted to AC voltage at the grid voltage level by the second block which is a DC/AC inverter power stage. A more detailed block diagram of Solar String inverter is available on TI's String inverter applications page.